Model-driven Development of Context-Aware Web Appl

Model-drivenDevelopmentofContext-AwareWebApplicationsStefanoCeri,FlorianDaniel,MaristellaMatera,FedericoM.FaccaDipartimentodiElettronica-PolitecnicodiMilanoP.zzaLeonardodaVinci,32-20133-Milano,Italyfceri,daniel,matera,[e-mail]-aware,multi-channelWebapplicationsaremoreandmoregainingconsensusfrombothcontentprovidersandconsumers,butveryfewproposalsexistfortheirconceptualmodeling.Thispaperillustratesaconceptualframeworkthatprovidesmodelingfacilitiesforcontext-aware,multi-channelWebapplications;italsoshowshowhigh-levelmodelingconstructscandrivetheapplicationdevelopmentprocessthroughautomaticcodegeneration.Ourworkstressestheim-portanceofuser-independent,context-triggeredadaptationactions,inwhichthecontextplaystheroleofa\¯rstclassactor,operatingindependentlyfromusersonthesamehypertexttheusersnavigate.ModelingconceptsarebasedonWebML(WebModelingLanguage),analreadyestablishedconceptualmodelfordata-intensiveWebapplications,whichisalsoaccompaniedbyadevelopmentmethodandaCASEtool.However,giventheirgeneralvalidity,theconceptsofthispapershapeupacompleteframeworkthatcanbeadoptedindependentlyfromthechosenmodel,method,andtool.CategoriesandSubjectDescriptors:H.1[InformationSystems]:ModelsandPrinciples;H.5.4[InformationInterfacesandPresentation(e.g.,HCI)]:Hypertext/Hypermedia;D.2.2[Soft-wareEngineering]:DesignToolsandTechniques|Computer-aidedsoftwareengineering(CASE)GeneralTerms:Design,LanguagesAdditionalKeyWordsandPhrases:Context,Context-awareness,Context-awareWebApplica-tions,ConceptualModeling,WebML,AdaptiveHypertext,AdaptiveHypermedia1.INTRODUCTIONAsWebapplicationsspreadinalmosteverydomain,novelchallengesareposedtodevelopers.ThecurrentadvancesinthecommunicationandnetworktechnologiesarechangingthewaypeopleinteractwithWebapplications,providingthemwithdi®erenttypesofmobiledevicesforaccessingatanytimefromanywhereandwithanymediaservicesandcontentscustomizedtousers'preferencesandusageenvironments.Moreandmoreusersthemselvesaskforservicesandapplicationshighlytailoredtotheirspecialrequirementsand,especiallyduetotheincreasinga®ordabilityofnewandpowerfulmobilecommunicationdevices,theyalsobegintoappreciatetheavailabilityofubiquitousaccess.Duetosuchpremises,newissuesAuthor'saddress:FlorianDaniel,DipartimentodiElettronicaeInformazione,PolitecnicodiMilano,P.zzaL.daVinci,32-20133-Milano-Italy.Permissiontomakedigital/hardcopyofallorpartofthismaterialwithoutfeeforpersonalorclassroomuseprovidedthatthecopiesarenotmadeordistributedforpro¯torcommercialadvantage,theACMcopyright/servernotice,thetitleofthepublication,anditsdateappear,andnoticeisgiventhatcopyingisbypermissionoftheACM,Inc.Tocopyotherwise,torepublish,topostonservers,ortoredistributetolistsrequirespriorspeci¯cpermissionand/orafee.c°20YYACM0000-0000/20YY/0000-0001$5.00ACMJournalName,Vol.V,No.N,Month20YY,Pages1{29.2¢StefanoCerietal.andrequirementsneedtobeaddressedforsupportingcontext-awareandmulti-channelaccesstoservicesandapplications.Context-awarenessisoftenseenasrecentlyemergedresearch¯eldwithininfor-mationtechnology,andinparticularwithinthedomainoftheWeb.Fromanotherperspective,itcanbehoweverinterpretedasnaturalevolutionofpersonalization,addressingnotonlytheuser'sidentityandpreferences,butalsotheinteractionenvironmentthathostsapplications.Personalizationhasalreadydemonstrateditsbene¯tsforbothusersandcontentprovidersandhasbeencommonlyrecognizedasfundamentalfactorforaugmentingthee±ciencyoftheoverallcommunicationofcontents.Context-awarenessgoesonestepfurtherinthesamedirection,aimingatenhancingtheapplicationusefulnessbytakingintoaccountawiderrangeofpropertiesthanpersonalization.ThesecondingredientformodernWebapplications,multi-channelaccess,isgain-ingaswellincreasingconsensusbybothcontentconsumersandproviders.Whiletheformeraremoreandmoreattractedbyportabledevicesequippedwithhigh-resolutioncolordisplays,abletoprovidesimilarbrowsingexperiencesastraditionaldesktopcomputers,thelatterareincreasinglyfacilitatedbystandardizedcommu-nicationprotocols(i.e.,HTTP)andmarkuplanguages(i.e.,HTML),supportedbymostofsuchdevices.Consequently,multi-channeldeploymentdoesnotany-morerequirecompletelydi®erent,paralleldesignapproachesandisthusbecomingratherapresentationproblemontopofuni¯edengineeringsolutions.Cost-e®ectivemulti-channeldevelopmentisthereforebecomingpossible,thus¯nallyraisingtheinclinationofcontentproviderstowardit.Inthispaperwetrytocombinethepotentialbehindthepreviousconsiderationsintoaconceptualframework,providingmodelingfacilitiesforcontext-aware,multi-channelWebapplications.Conceptualmodelingmethodshavealreadyprovedtheire®ectivenessforthedesignofpersonalizedWebapplications(seeforexample[Cerietal.1999;Schwabeetal.2002]).However,veryfewproposalsexistfortheconcep-tualmodelingofreactive,context-awareWebapplications.Thispaperwillthereforeintroducesomemodelingprimitivesabletocapturethesemanticsofreactivebe-haviors,andwillalsoshowhowhigh-levelconstructscandrivethedevelopmentprocessthroughautomaticcodegeneration.Di®erentlyfrommostconventionaladaptivehypermediasystems,whichmainlyaddre